There are a wide variety of rechargeable batteries available today for use as energy sources, including for use as backup energy sources. Lithium-ion batteries are one type of rechargeable battery in which lithium-ions move from a negative electrode to a positive electrode during discharge and back when charging. An intercalated lithium compound is used in a lithium-ion battery as one electrode material. The electrolyte, which allows for ionic movement, and the two electrodes are constituent components of a lithium-ion battery cell. A cell is a basic electrochemical unit that contains the electrodes, separator and electrolyte. A battery or battery pack is a collection of cells or cell assemblies. These may be ready for use by providing an appropriate housing, and electrical interconnections.
Recent events have highlighted the potential for thermal runaway events with the application of lithium-ion technology-based batteries. These events have typically been associated with two different types of causes, namely, an internal short circuit associated with a manufacturing or design defect, or a catastrophic failure due to an external event, such as an external heating event (e.g., fire). In either case, the triggering of the thermal runaway event is typically due to the degradation of the separator layer within the battery, thereby allowing the inception of an exothermic reaction to occur.